Friction elements



. pitch, rubber and so on.

Patented Aug. 28, 1945' Mortimer '1. Harvey, East Orange; N.

to Harvel Research Corporation,

of New Jersey- J., assignor a corporation Serial No. 395,394

No Drawing. Application-May 27, 1941, i

3 Claims. (01. zoo-cs) The present invention relates generally tofriction elements and more particularly the present invention relates tolinings for brakes and clutches made of compositions comprisinggranulated particles of polymerized furane compounds.

Heretofore the friction fortifying dusts for friction elements generallyhave been phenol-aldehyde condensation products or such condensationproducts which have been modified-by addition of materials such asdrying oils before condensation has been completed.

I have found that the furane compounds can be polymerized to a state inwhich they are infusible yet can be softened slightly at 500-600 F. to arubbery condition and that powders or dusts made of such polymerizedfuranes or modifications thereof are adapted for dustsin frictionelements. 1

Modifications of polymerized furanes can be made by mixing in othermaterials with the furane compound before polymerizing so that thefurane dust particle has incorporated with it a greater or smalleramount of the added material. These other materials are added, forexample, for obtaining certain frictional characteristics attemperatures below those at which the polyfurane becomes slightlysoftened, the added material being adapted to soften at temperatureslower than those at which the polyfuranes soften so that, in thefinished article such as a brake lining, for example, a slight softeningwhich is less than actual fusing is obtained over a wide range oftemperature or at different ranges. Examples of materials adapted foraddingto the polyfurane are vegetable oils such as perilla, linseed andchina wood oils, fatty acids such as stearic, oleic and linoleic acids,hardwood pitch, fatty acid still residues such as cottonseed oilIllustrative examples of the furane compounds suitable for use in thepractice of the present invention are furane, C4H4O; furfuraldehyde,C4H3O-CHO; furfuryl alcohol,

(canto-onion) ethyl furoate (CfiO-COOCfi); coumarone (benzofurane,CaHsO) and hvdrofuramide,

(C4H3OCH)3N2 and other furane compounds which can be polymerized by themethods disclosed or referred to ride, aluminum chloride, phosphoricacid, hydrochloric acid,.sulphuric acid, 'alkyl sulphates and alkylphosphates and mixtures of any two or more of these, for example amixture of four parts of diethyl sulphate and one part of concentratedsulphuric acid. The alkyi radicles on the alkyl phosphates and alkylsulphates can be methyl, ethyl, propyl, butyl or amyl, for illustrativeexamples, and the alkyl compounds used can be m no alkylor dialkylsulphate or the mono, di or trl-alkyl phosphate. Reference is herebymade to patents numbers 1,665,233 to 1,665,237, inclusive, forillustrative methods of polymerizing furane compounds.

Illustrative examples of methods for making the frictional granulatedpowders Or dust of the present invention are given as follows! Example1.-About one hundred parts by weight of furfuraldehyde and ten parts ofconcentrated hydrochloric acid are mixed'together and heated to about C.for from about five to ten minutes or until a gelatinous product isobtained. The gelatinous product is then cured in pans at about C. to C.for about eighteen to about twenty-four hours to obtain a hard vparts offurfuraldehyde are heated togetherat 50-80 C. until solution occurs andtwenty parts of diethyl sulphate are. added and the mixture held at thistemperature for about four to sixteen hours until solidification occurs.The product is a dense tight mass and iscooled' and ground to the sizerequired. At higher temperature. e. 8. 100 C. frothing occurs and thegranular structure is not obtained.

Example 3.-About three hundred parts by weight of cottonseed oil pitch,one'hundred parts of furfuralcohol and forty parts of diethyl sul phateare mixed together and heated to from about 25 C. to about 70 C. untilthere is prodiiced a hard, solid product which can be gran- 'ulated'.The polymerization reaction is faster than when furfuraldehyde is usedand .can be brought about in from about twelve to about three hours,depending onthe temperature at which the reaction is conducted.-

Example 4.About one hundred parts by weight of furfuralcohol and twentyparts of diethyl sulphate are mixed together and left to stand at about25 C. to about 30 C. for several days. Condensation reaction occurs andthe weight of cottonseed oil pitch and one hundred parts offurfuraldehyde are heated together at from 50 C. to 80 C. until solutionoccurs when there is added a solution of two parts of sulphuric acid infifteen parts of diethyl sulphate and the mixture held at thestatedtemperature until solidification occurs to form a dense, tight masswhich is cooled and ground or granulated to the required size.

The method of this example is similar to that of Example 2 above withthe difference that a solution of sulphuric acid in diethyl sulphate isused in place of the diethyl sulphate alone of said Example 2. With thesolution of sulphuric acid in diethyl sulphate (or other alkyl sulphate)the polymerization reaction is initiated sooner and the speed ofpolymerization is increased, and the solid, pulverizable polymerizationproduct is obtained in less time than with the diethyl (alkyl) sulphatealone.

Example 6.About one hundred parts by Weight of iurfuraldehyde and tenparts of concentrated hydrochloric acid are mixed together and heated at100 C. for about five to ten minutes or until a gelatinous mass isobtained after which the temperature is raised to about 110 C. to 115 C.for about eighteen to twenty-four hours or until a hard, tough solidmaterial is obtained which can be ground or pulverized.

Example 7.--About one hundred parts by weight of furfuramideand fortyparts of diethyl sulphate are mixed together and heated to from about 50C, to about 100 C. A vigorous reaction is obtained which in a short timeproduces an inlusible mass which is solid and which can be ground orgranulated.

Example 8.About one hundred parts by weight of furfuraldehyde, onehundred parts of linseed oil and twenty parts of diethyl sulphate aremixed together and heated to from about 50 C. to about 80 C. until agelatinous mass is produced when the temperature is raised to about 110C. to 115 C. until a hard brittle product is obtained, which product canbe ground or granulated.

Example 9.About one hundred parts by weight of a fraction of gas housedrip boiling between 150 C. and 200 C., and containing indene andcoumarone (benzofurane), and five parts of diethyl sulphate were mixedtogether and heated for three hours at 140 C. and then for three hoursat 120 C. or until a hard brittle resin is obtained which can be groundor granulated.

Reference is hereby made to patents numbers, 2,164,326 and 2,165,140 forexamples of friction elements in which granulated particles are used forfrictional characteristics. The polymerized iurane composition in thegranulated form as described herein can be substituted for any partorall of the infusible phenolic resin in the pulverized form of Examples1, 2 and 3 of said patent 2,164,326,

A further illustrative example of friction elements which can be made upwith granulated polymerized furanes, is as follows:

Example A.About sixty parts by weight of asbestos fiber, fifteen partsof dry, finely powdered heat reactive phenol-aldehyde resin (for.

binder), fifteen parts of a granulated, hard, in-

- fusible furane olymer (polymerized iuriuraldehyde or polymerizedfurfuryl alcohol, for illustrative examples) and ten parts of bariumsulphate are mixed together, dry in a tumbling bar'- rel, Whenthoroughly mixed the mixture ,is pressed into sheets with theapplication of heat and pressure sumcient to cause the binder to fiowand to give it a preliminary set, but not sufilclent for the binder toreach a final state of curing. The sheets are then cut to size and curedin molds to the final state of the binder to form curved brake linings.

For clutch facing the heat and pressure, when desired, can be sufficienton the first pressing to set the binder to the final state, the shapesbeing formed after the final setting. In other cases the shapes of theclutch facing can be formed before the final setting.

Generally the furane compounds used in the practice of the presentinvention are produced by polymerization under acid conditions, thedialkyl sulphate and trialkyl phosphates of the examples being slightlyacidic but it is intended that furane compounds that are first subjectedto alkaline conditions and finally to acidic polymerizing conditions areproducts suitable for making the hard particles of polymerized furanecompounds used in the practice of the present invention.

While only diethyl sulphate is recited in the examples as the alkylsulphate polymerizing agent it is pointed out that any of the otherpolymerizing agents recited above can be substituted in said examplesfor the diethyl sulphate, and generally in substantially equal amounts.Also, while cottonseed oil pitch in the examples is the only materialused with a furane compound and that only in amounts equal to the amountof iurane compound used, it is to be understoodany one or more of theother compounds or materials can be used in place of all or any part ofthe cottonseed oil pitch. Further, the proportion cottonseed oil pitch(or its equivalent) to furane compound can be varied, for example, fromfour parts of cottonseed oil pitch (or its equivalent) to one offurfuraldehyde (or its equivalent) down to the other extreme where onlya furane compound (or compounds) is used.

Having thus described my invention, what I claim and desire to protectby Letters Patent is:

1. A brake lining comprising asbestos, organic friction material and aphenol-aldehyde resin binder, said organic friction material comprisingcomminuted particles of a product selected from the group consisting ofsolid infusible condensation products of furfuryl alcohol in thepresence comminuted particles of a solid infusible condensation productof furfuraldehyde in the presence of an acidic agent.

MORTIMER T. HARVEY.

